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Subject[PATCH 4.19 206/276] x86/uaccess, ftrace: Fix ftrace_likely_update() vs. SMAP
Date
[ Upstream commit 4a6c91fbdef846ec7250b82f2eeeb87ac5f18cf9 ]

For CONFIG_TRACE_BRANCH_PROFILING=y the likely/unlikely things get
overloaded and generate callouts to this code, and thus also when
AC=1.

Make it safe.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
kernel/trace/trace_branch.c | 4 ++++
1 file changed, 4 insertions(+)

diff --git a/kernel/trace/trace_branch.c b/kernel/trace/trace_branch.c
index 4ad967453b6fb..3ea65cdff30d5 100644
--- a/kernel/trace/trace_branch.c
+++ b/kernel/trace/trace_branch.c
@@ -205,6 +205,8 @@ void trace_likely_condition(struct ftrace_likely_data *f, int val, int expect)
void ftrace_likely_update(struct ftrace_likely_data *f, int val,
int expect, int is_constant)
{
+ unsigned long flags = user_access_save();
+
/* A constant is always correct */
if (is_constant) {
f->constant++;
@@ -223,6 +225,8 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val,
f->data.correct++;
else
f->data.incorrect++;
+
+ user_access_restore(flags);
}
EXPORT_SYMBOL(ftrace_likely_update);

--
2.20.1


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